https://orcid.org/0000-0003-1907-2218
ABSTRACT
Senate Bill 277 (SB277) eliminated nonmedical exemptions for school-entry vaccines in California, but the impact of parental vaccine knowledge, attitudes, and beliefs on vaccine decision-making has not been extensively examined within the post-SB277 context. This study generates preliminary understanding and discussion of the vaccination knowledge, attitudes, and beliefs among a pilot population of parents of kindergarten students in California after the implementation of SB277. School officials administered a cross-sectional survey to parents of kindergarten children in California from April to July 2019. Parents reported their perceptions of diseases and vaccines, key immunization beliefs, and confidence in different sources of vaccine information. Most parents (92%) had fully vaccinated their children post-SB277 and generally perceived vaccines to be safe and effective, but about 44% reported they were hesitant about childhood vaccines. The majority of parents (87%) rated vaccine information from their doctor as highly credible. This pilot group of kindergarten parents was generally supportive of vaccination and had fully vaccinated their children, but most parents still harbored concerns and misconceptions about vaccines and about public health authorities. This indicates a disconnect between parental vaccine compliance and confidence, and suggests that educational interventions could impact parental vaccine behavior and decision-making.
Large-scale vaccination programs have proven to be one of the most successful and cost-effective public health interventions of all timeCitation1. However, despite the extensive benefits of vaccination, many parents harbor concerns about vaccine safety and efficacy.Citation2–5 Vaccine hesitancy and refusal have contributed to lower vaccine coverageCitation2,Citation6–9 and increased infectious disease outbreaks.Citation6–11 Many parents and providers are no longer familiar with infectious diseases that were previously feared but have been effectively eliminated by vaccination.Citation2 Nearly 77% of parents in the United States report concerns about adverse side effects and the efficacy of vaccines, with one in three parents holding serious concerns about the number of vaccines given concurrently, vaccine ingredients, and the potential for adverse health outcomes.Citation12
In the United States, state-level legislation has made vaccination against many infectious diseases mandatory for every child entering kindergarten, as well as those entering daycare, middle school, and sometimes college.Citation13 All states allow medical exemptions from the requirements for children with a contraindication to vaccination, and some states allow parents with religious or philosophical objections to opt-out of required vaccinations by obtaining a nonmedical exemption.Citation14 Amid growing vaccine refusal and subsequent infectious disease outbreaks in the last several decades, particularly measles,Citation7,Citation15,Citation16 several state legislatures have removed the nonmedical exemption option or made these types of exemptions more difficult to obtain. In 2015, California passed Senate Bill 277 (SB277) eliminating all nonmedical exemptions to school vaccination requirements.Citation17 After widespread measles outbreaks in 2019, New YorkCitation18 and MaineCitation19 passed similar legislation to eliminate all nonmedical exemptions, and Washington eliminated nonmedical exemptions for measles-mumps-rubella vaccine specifically.Citation20
Parental misperceptions about vaccine risks and benefits, lack of time for vaccination discussions during pediatric visits, and logistical requirements for vaccination all contribute to vaccine refusals and delays.Citation21–23 More than 70% of parents trust the immunization advice they receive from their child’s health-care provider,Citation24 indicating that pediatric providers remain important advocates for vaccination in the clinical setting. However, in practice there is typically a limited time for detailed questions and individually tailored messaging,Citation21 preventing providers from thoroughly discussing vaccination with parents.
Understanding why parents have concerns about vaccination is crucial for identifying and addressing gaps in parental knowledge. Parental concerns about vaccine safety and efficacy can result in vaccine refusal and under- or un-vaccinated children.Citation25–28 Many factors impact how parents feel about vaccines, but the impact of parental vaccine knowledge, attitudes, and beliefs on vaccine decision-making has not been extensively examined within the post-SB277 context in California.Citation29–31 This study aimed to characterize the vaccination knowledge, attitudes, and beliefs among a pilot sample of parents of kindergarten students in California after the implementation of SB277. To our knowledge, this is the first study of parental vaccine knowledge, attitudes, and beliefs after a policy such as SB277 has been implemented.
In the present study, school officials administered a cross-sectional survey (Appendix 1) to parents of kindergarten children in California from April to July 2019. To be eligible to participate, parents had to be age 18 or older, live in California, and have at least one child in kindergarten in the 2017–18 school year. We limited survey participants to parents of kindergarten students because these children would not have had a prior nonmedical exemption. Existing nonmedical exemptions were grandfathered under SB277 and as such older children may still have held nonmedical exemptions.Citation30–32
Our team completed a larger study that surveyed schools regarding immunization practices, and a subset of these schools agreed to participate in the present study. We used a publicly available list of all California schools from the California Department of Education to identify eligible schools and obtain school contact information. Independent study programs, homeschooling private school programs, and schools without kindergarten were removed from the sampling frame. We contacted each school to identify the person at each school who was responsible for the administration and enforcement of vaccine requirements, such as the school nurse, health clerk, registrar, or front office clerk. We contacted the school officials ahead of time to inform them of the study and to request their participation. A member of the research team then visited schools that agreed to participate who reviewed all necessary study materials, showed the school official how to randomly select kindergarten parents, and answered any questions. School administrators prepared lists of kindergarten students categorized by vaccination exemption status so that students with temporary or permanent medical exemptions and no exemptions could be randomly selected. School administrators then randomly selected students using a random number generator and contacted their parent(s) for the survey. We surveyed up to 14 kindergarten parents per school, ideally with seven parents of up-to-date students and seven parents of not up-to-date students. However, at many schools, all of the kindergartners were up-to-date on vaccines, and as such up to 14 parents of only up-to-date students would have been surveyed. We originally aimed to survey up to 14 parents per school at 125 California schools for a total of 1,750 parents of kindergarten parents as part of a larger parent study; due to unforeseen challenges with data collection, we ultimately conducted data collection at only 16 schools.
School officials provided parents with an overview of the survey intention and content before participating. Schools then administered the survey to parents in either English or Spanish. School officials mailed survey packets to parents containing a disclosure letter, postcard to return to the school, the survey, a 5 USD gift card incentive, a pen, and an envelope for the parent to return their completed survey to the researchers. The schools followed up with parents who did not respond by sending two follow-up letters and an additional survey packet and telephoning them to encourage participation. Those who did not respond after two rounds of follow-up were considered non-responders. These survey procedures allowed school officials to follow up with non-responders while keeping parental information confidential from the researchers. Parents had the option to complete the survey either by mail or online via the web-based software Qualtrics (Provo, UT).
Parents reported their child’s vaccination status (up-to-date, temporary or permanent medical exemption, or conditional enrollment), whether the child had not received one or more vaccines required for school entry, whether their older children had a nonmedical exemption, and whether their doctor or school made them aware of the risks of not vaccinating their kindergartner.
We used five-point Likert scales previously developed and used by the research teamCitation25,Citation33–38 to ask participants to estimate the probability that an unvaccinated child in California would contract a vaccine-preventable disease (measles, mumps, influenza, pertussis, and varicella) by age 12 (“impossible” to “very likely”), how serious it would be for an 8-year-old to develop one of these diseases (“not at all serious” to “very serious”), how effective the vaccines are in preventing children from getting these childhood diseases (“not at all effective” to “very effective”), how safe the vaccines are (“not at all safe” to “very safe”), eight questions relating to key vaccination beliefs (“strongly agree” to “strongly disagree”), and the quality of nine sources for vaccine information (“excellent source” to “extremely poor source”).
We dichotomized responses to questions on key vaccination beliefs into “strongly agree” or “agree” versus all other responses. We dichotomized the quality of sources for vaccine information into an “excellent” or “good” source versus all other responses. We evaluated vaccine knowledge, attitudes, and beliefs in the study population using descriptive statistics including measures of frequency, central tendency, and variation (Stata version 14, College Station, TX). This study was approved by the Institutional Review Board at Emory University.
Sixteen schools sent the survey to 252 kindergarten parents in early 2019; of these, 85 (34%) completed the survey. Of the 15 schools that returned surveys, five were private schools (33%) and 10 were public (67%). School-level parent response rates ranged from 0% to 82% among the 15 schools, with an overall parental response rate of 34%. Roughly 78% of respondents were mothers, and more than 70% were aged 26 to 45 years (). About 41% of parents reported being white, 29% as Hispanic or Latino, and 19% as Asian or Pacific Islander. About 52% of respondents had attended college and 26% had received post-graduate education. About 38% of parents reported household income from 30,000 USD to 99,999, USD and 35% reported income over 100,000. USD
Table 1. Demographic characteristics of kindergarten parents in California participating in study (n = 85)
Of the 85 parents that responded, 78 (92%) reported that their child was fully vaccinated upon entering kindergarten. Five parents (6%) reported that their child had a medical exemption, and two did not know their child’s vaccination status. Parents of up-to-date and not up-to-date children were similar in terms of race and household income. Eighty-one parents (95%) reported that they were aware of California laws requiring their child to be fully vaccinated for school, and of these 15 (19%) reported that these laws influenced their decision to vaccinate their kindergartner. Only 39% of parents reported they were aware of SB277 specifically. Eighty percent of parents reported that their kindergartner would be fully vaccinated even if there were no laws requiring vaccines for school entry in California.
About 44% of parents reported they were “very hesitant” or “somewhat hesitant” about childhood vaccines. Among the five vaccine-preventable diseases included in the survey, parents perceived that their kindergarten children were most susceptible to influenza and varicella, and less susceptible to pertussis, mumps, and measles. Parents perceived pertussis, mumps, and measles as slightly more severe diseases and influenza and varicella as slightly less severe. All parent participants perceived all vaccines included in the survey to be safe, but they also perceived influenza vaccines to be slightly less effective.
Surprisingly, many parents agreed or strongly agreed with a number of vaccine-hesitant statements despite the majority of parents reporting their kindergarten child was up-to-date on vaccinations (). Specifically, 91% reported it is better for children to get fewer shots at the same time, 72% reported that the Centers for Disease Control and Prevention (CDC) and Advisory Committee on Immunization Practices (ACIP) underestimate the frequency of side effects, 58% reported that children get more shots than are good for them, 40% reported that children’s immune systems are weakened by too many vaccines, 36% reported that parents should be allowed to send unvaccinated children to school, and 34% reported it is better to develop immunity by contracting the disease rather than by getting vaccinated. Most parents reported they trust the information they receive about vaccines (91%) and that immunization requirements protect children from getting diseases from unimmunized children (92%).
Table 2. Proportion of parents agreeing with vaccine-related beliefs by child vaccination status
Parental confidence in vaccine information from different sources varied widely. The majority of parents (87%) rated vaccine information from their doctor as highly credible (). To a lesser extent, parents also reported the California Department of Public Health (57%), CDC (66%) and Food and Drug Administration (FDA) (57%) as highly credible. Very few parents (3%) rated social media as a highly credible source of vaccine information, but a greater proportion of parents rated vaccine information from other less reputable sources like alternative doctors (26%), and Dr. Bob Sears (46%), a California physician known for promoting alternative vaccination schedules,Citation39 as highly credible. Interestingly, 67% of parents rated the National Vaccine Information Center, a nonprofit anti-vaccine organization, as a credible source – higher than those reporting the California Department of Public Health, CDC, and FDA as highly credible.
Table 3. Parental perceptions of credibility of sources for vaccine information by child vaccination status
In this study, we characterized the vaccine knowledge, attitudes, and beliefs of parents of kindergarten students after the passage of SB277, which substantially tightened nonmedical vaccine exemptions in the state of California. Our results suggest parental attitudes may impact child vaccination status, but the significance of these associations may have been limited by the recent legislation and by our sample size. Perhaps more importantly, we found that kindergarten parents were generally supportive of vaccination and had fully vaccinated their children, but many parents still harbored concerns and misconceptions about vaccines. We found that most parents fully vaccinated their kids for school entry despite their concerns about vaccines, which may indicate that legislative changes could impact parental vaccine decisions and behaviors (even for vaccine-hesitant parents). The present study provides important insight into whether and how California’s removal of nonmedical exemptions may have impacted the vaccine-related attitudes, beliefs, and practices of parents of kindergarten-age children.
We found that vaccination concerns and misinformation were prevalent among all parents, regardless of child vaccination status. These results are consistent with previous findings.Citation25,Citation40 This demonstrates the need for comprehensive interventions for all parents to ensure that they continue to adhere to vaccine recommendations in order to protect their child from infectious disease, rather than solely to abide by school immunization law. This has important implications for disease control, as even small clusters of misinformation and vaccine refusal can have substantial impacts on herd immunity.Citation8,Citation41 This apparent disconnect between high vaccine compliance and high vaccine hesitancy is interesting but worrying; our results indicate that many parents of up-to-date children have substantial concerns about vaccines. The high levels of problematic beliefs about vaccination among parents who fully vaccinate their children is important and salient, as it points to the impact of SB277 among parents who might otherwise not be fully vaccinating their children. This suggests that vaccine compliance may not automatically result in higher vaccine confidence. The high parental hesitancy observed in this study is a worrying indicator of suboptimal support in an essential component of our disease prevention and public health systems.
Parents generally perceived required childhood vaccines as safe and efficacious. Parental perceptions of disease susceptibility and severity somewhat contradicted the consensus from public health authorities, particularly with parents underestimating the severity of influenza and the susceptibility to pertussis and measles. The latter is particularly worrying given recent outbreaks of pertussis and measles in California specifically. Eighty percent of parents reported that their kindergartner would be fully vaccinated if there were no laws requiring vaccines for school entry in California, and 92% of parents reported their child was up-to-date on vaccines. Likewise, 18% of parents reported that California laws surrounding vaccination influenced their decision to vaccinate their kindergartner, so our primary outcome of up-to-date status may not have accurately reflected parental views on vaccination.
Responses indicating confidence in different public health authorities were somewhat mixed, with only of about 60% of parents rating the CDC, FDA, and the California Department of Public Health as highly credible sources of vaccine information. This could indicate lower trust in public health authorities in this population, perhaps due to perceived association with the controversial vaccine legislation changes. Worryingly, a higher proportion of parents rated the anti-vaccine National Vaccine Information Center as a credible source. This may have been due to the organization name appearing credible as well as unfamiliarity with the organization, and this suggests an urgent need for vaccine education among this parent population. School officials or vaccine champions may be effective in combating this issue by educating parents on how to access the most accurate and up-to-date vaccine data from trusted sources. The moderate levels of trust in public health authorities are also disturbing and suggest that interventions may be necessary to improve parental trust and confidence in public health. Future studies could explore whether working to improve parental trust in public health authorities is an effective mechanism for improving confidence in vaccination among parents, and subsequently improving vaccine acceptance. Paired with the level of vaccine hesitancy we observed, this moderate confidence in public health authorities also engenders concern that parents may be mistrusting of public health measures surrounding vaccination. Educating parents on the rationale behind public health measures like the elimination of nonmedical exemptions may help to reduce confusion, improve trust in public health authorities, and improve confidence in vaccines.
There are parents in California who ultimately decide not to vaccinate. The elimination of nonmedical exemptions in California led to an increase in medical exemptions, many of which were provided under dubious circumstances.Citation32 Parents may select health-care providers who have a reputation of being more sympathetic to vaccine hesitant parents and who are more willing to write medical exemptions despite a lack of valid medical contraindications to vaccination. One notable example is Dr. Bob Sears, whose medical license was temporarily revoked in 2018 for inappropriately writing unnecessary medical exemptions.Citation42 This increased demand for medical exemptions may also create substantial time burdens for providers who are discussing these issues with hesitant parents. In late 2019, new legislation SB276 was passed to ensure medical exemptions are being granted under proper conditions; the bill requires the California Department of Public Health to review all medical exemptions from schools where less than 95% of students are up-to-date on vaccines, and to review all medical exemptions from physicians who wrote more than five medical exemptions.Citation43
This study had several limitations. We are unable to examine vaccine knowledge, attitudes, and beliefs among parents before and after the passage of SB277 in California. There may have been selection bias in the participating schools as only schools with willing and motivated school officials agreed to assist with the parent surveys. The response rate may have been impacted by the length of the survey and the willingness of school officials to follow up with non-responders. It is likely that only parents with an interest in vaccines and SB277 completed the survey, resulting in response bias if their responses differ from parents who did not complete the survey. However, legal and privacy considerations involved sampling in schools contribute to the functional challenges in recruiting a larger sample of parents of kindergarten students. We were unable to compare the knowledge, attitudes, and beliefs of parents who accepted and refused to complete the survey, since no information was collected from refusers and the submitted surveys were anonymized. Our study provides a unique and topical snapshot after the elimination of nonmedical exemptions and characterizes an important aspect of vaccine decision-making. Parents of homeschooled children were not included in this survey, but other studies from our research team have examined this group.Citation29,Citation44 Additionally, we are unable to determine causality between parental vaccine knowledge, attitudes, and beliefs and self-reported vaccination status of their children. Further studies should be conducted to determine how perceived vaccine risks and benefits can impact parental decision-making and child vaccination status.
Our results generate preliminary understanding and discussion of parental knowledge, attitudes, and beliefs in a pilot population of California parents after the implementation of SB277. Additional research is needed to broaden the sample size and assess the wider generalizability of these findings. Future research should also develop, implement, and evaluate programs designed to effectively communicate with parents and improve vaccine coverage. Parental education about the importance of vaccination may help to resolve the disconnect between parental vaccine compliance and confidence. In particular, tailored information on vaccination can also be beneficial for dispelling misinformation and addressing parental concerns.Citation2,Citation45 In other states that have recently eliminated nonmedical exemptions, further research could explore how parents respond to this type of legislation and assess whether their vaccine-related knowledge and beliefs change over time.
Disclosure of Potential Conflicts of Interest
Dr. Klein has received research support from Merck, Pfizer, GlaxoSmithKline, Sanofi Pasteur, and Protein Science (now Sanofi Pasteur).
Acknowledgments
This work was supported in part by the National Institutes of Health R01AI125405. We would like to thank our graduate research assistants at Emory University, in particular Erin Swendsen, for their assistance with the data collection for this study.
Additional information
Funding
References
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